Conventional communication system switches, such as private branch exchanges (PBXs) and other premises-based telephone switches, generally support a wide variety of useful features, such as bridged call appearances, hunt groups, call forwarding, navigable directories, multi-call conferencing, etc. However, these and other switch-based features are typically provided only to those user terminals that represent internal extensions within the premises serviced by the switch. As a result, a user terminal associated with an external network is generally unable to avail itself of the full set of features supported by the switch.
Bridging has been employed, for example by the EC500™ product of Avaya Inc., to provide not only one-number portability and one-number access to anyone in an enterprise network but also to permit a user at an external originator terminal, specifically a cellular phone, to direct a call to a designated remote access extension to access switch features. Such features can include, e.g., bridged call appearances, hunt groups, call forwarding, navigable directories, multi-call conferencing or any other features supported by the switch. The remote access extension is administered as a number on the switch that may be directly dialed from the originator terminal. When a call to this extension is received in the switch, the switch maps the corresponding identifier to an entry in a stored list of external terminals and connects the call. Once access is granted, particular switch features may be activated by entry of feature access codes by the user or by DTMF signaling. Specifically, remote access may be implemented through the use of one or more abbreviated dialing entries on an abbreviated dialing list. For example, an inputted DID number is converted into a new digit string, such as *7001 (which contains feature access code *70 for a designated abbreviated dialing list plus a dial code 01 for remote access extension entry. This remote feature access functionality is further discussed in copending U.S. patent application Ser. Nos. 09/908,156 and 09/908,155, both filed Jul. 18, 2001.
This approach can have drawbacks. For example, to invoke a feature with a feature access code the user must dial a special direct inward dialing (DID) number to access the switch followed by a series of codes to access only a limited set of features. The features accessible are only those accessible by a trunk-based mode (i.e., by an analog telephone) without the ability to use a flash functionality. As used herein, the terms “trunk” and “trunk line” should be understood to include POTS telephone lines, integrated services digital network (ISDN) lines, T1 lines or various portions or combinations of these and other types of transport media.
Another approach to remotely access features is by means of a “softphone” or software-controlled communication device. A normal personal computer or PC can be converted into a softphone by processing specialized call functionality software. The softphone provides the user with a telephone interface and the ability to conduct conversations using the PC's speakers and microphones. The softphone generally has the same features as a telephone designed to work with a switch, such as a PBX. This approach can work well but requires the use of a device that can be downloaded with emulation software. It also requires the device to establish a direct control link with the switch.